U.S. patent application number 15/869429 was filed with the patent office on 2018-07-19 for fluid loss estimation based on weight of medical items.
The applicant listed for this patent is Gauss Surgical, Inc.. Invention is credited to Siddarth SATISH, Julian THAYN.
Application Number | 20180199827 15/869429 |
Document ID | / |
Family ID | 62838383 |
Filed Date | 2018-07-19 |
United States Patent
Application |
20180199827 |
Kind Code |
A1 |
SATISH; Siddarth ; et
al. |
July 19, 2018 |
FLUID LOSS ESTIMATION BASED ON WEIGHT OF MEDICAL ITEMS
Abstract
A computer-implemented method for quantifying fluid includes
estimating a first volume of a first fluid contained in an item
based on a difference between a dry weight and a wet weight of the
item, and displaying a graphical representation of a container
containing a volume of a second fluid and a second volume of the
first fluid, wherein the graphical representation includes a first
display element for receiving a first user input indicating the
volume of the second fluid in the container, and a second display
element for receiving a second user input indicating a total fluid
volume in the container, estimating the second volume of the first
fluid based on at least one of the first and second user inputs,
and estimating a quantity of the first fluid based on the first and
second volumes of the first fluid.
Inventors: |
SATISH; Siddarth;
(Cupertino, CA) ; THAYN; Julian; (Mountain View,
CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Gauss Surgical, Inc. |
Los Altos |
CA |
US |
|
|
Family ID: |
62838383 |
Appl. No.: |
15/869429 |
Filed: |
January 12, 2018 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62446333 |
Jan 13, 2017 |
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A61B 5/7475 20130101;
A61M 2205/3393 20130101; A61M 1/0001 20130101; A61B 5/02042
20130101; A61B 2505/05 20130101; A61B 5/7278 20130101; G01G 23/365
20130101; A61F 2013/8491 20130101; G01G 19/414 20130101; A61B 5/743
20130101; A61B 5/7435 20130101; A61B 10/0048 20130101; A61F 13/36
20130101 |
International
Class: |
A61B 5/02 20060101
A61B005/02; G01G 19/414 20060101 G01G019/414; A61B 5/00 20060101
A61B005/00; A61M 1/00 20060101 A61M001/00; A61F 13/36 20060101
A61F013/36; A61B 10/00 20060101 A61B010/00 |
Claims
1. A computer-implemented method for quantifying fluid from a
patient, the method comprising: estimating a first volume of a
first fluid contained in at least one item, based on a difference
between a dry weight of the item and a wet weight of the item;
displaying a graphical representation of a container on a display,
the container containing a volume of a second fluid and a second
volume of the first fluid, wherein the graphical representation
comprises a first display element for receiving a first user input
indicating the volume of the second fluid in the container, and a
second display element for receiving a second user input indicating
a total fluid volume in the container; estimating the second volume
of the first fluid in the container based on at least one of the
first and second user inputs; and estimating a quantity of the
first fluid based at least in part on the estimated first and
second volumes of the first fluid.
2. The method of claim 1, further comprising identifying a weighing
event corresponding to the item being placed on a scale and
receiving the wet weight in response to identifying the weighing
event.
3. The method of claim 2, wherein identifying a weighing event
comprises detecting a weight meeting a predetermined threshold
value.
4. The method of claim 3, wherein identifying a weighing event
comprises detecting a weight meeting the predetermined threshold
weight for at least a predetermined period of time.
5. The method of claim 1, wherein estimating a first volume of a
first fluid contained in at least one item comprises determining
the difference between a dry weight of the item and a wet weight of
the item and dividing the difference by a density of the first
fluid.
6. The method of claim 1, further comprising estimating a third
volume of the first fluid contained in at least a second item,
based on a difference between a dry weight of the second item and a
wet weight of the second item, and updating the estimated quantity
of the first fluid to include the estimated third volume of the
first fluid.
7. The method of claim 1, further comprising receiving a user input
indicating a quantity of at least one item type and receiving a dry
weight associated with the item type.
8. The method of claim 1, wherein at least one of the first and
second display elements in the graphical representation of the
container comprises a user-manipulable sliding marker.
9. The method of claim 1, wherein the graphical representation is
generally triangular, and the first display element corresponds to
volume of amniotic fluid, and the second display element
corresponds to volume of blood.
10. The method of claim 1, further comprising displaying the
estimated quantity of the first fluid on the display.
11. The method of claim 1, wherein estimating a quantity of the
first fluid comprises estimating a volume of the first fluid.
12. The method of claim 1, wherein estimating a quantity of the
first fluid comprises estimating a volumetric rate of loss of the
first fluid.
13. The method of claim 1, further comprising alerting a user if
the estimated quantity of the first fluid meets a predetermined
threshold.
14. The method of claim 1, further comprising receiving an
aggregate weight of one or more weighed items of an item type and
estimating a number of weighed items based at least in part on the
aggregate weight and a dry weight associated with the item
type.
15. The method of claim 1, further comprising estimating a quantity
of the first fluid further based at least in part on an estimated
third volume of the first fluid.
16. The method of claim 15, further comprising displaying a third
display element for receiving a third user input indicating the
estimated third volume of the first fluid in a second
container.
17. A system for quantifying fluid from a patient, the system
comprising: a scale configured to measure a wet weight of at least
one item containing a first volume of a first fluid; a display
configured to display a graphical representation of a container
containing a volume of a second fluid and a second volume of the
first fluid, wherein the graphical representation comprises a first
display element for receiving a first user input indicating the
volume of the second fluid in the container and a second display
element for receiving a second user input indicating a total fluid
volume in the container; and a processor coupled to the scale and
the display, wherein the processor is configured to: estimate the
first volume of the first fluid in the item based on a difference
between a dry weight of the item and the wet weight of the item;
estimate the second volume of the first fluid in the container
based on at least one of the first and second user inputs; and
estimate a quantity of the first fluid based at least in part on
the estimated first and second volumes of the first fluid.
18. The system of claim 17, wherein the scale is a wireless scale
configured to communicate wirelessly with the processor.
19. The system of claim 17, wherein the processor is configured to
identify a weighing event corresponding to the item being placed on
the scale, and further configured to receive the wet weight of the
item in response to identifying the weighing event.
20. The system of claim 19, wherein the processor is configured to
identify the weighing event by detecting a weight meeting a
predetermined threshold value.
21. The system of claim 20, wherein the processor is configured to
identify a weighing event by detecting a weight meeting the
predetermined threshold weight for at least a predetermined period
of time.
22. The system of claim 17, wherein the processor is configured to
estimate a first volume of a first fluid by determining the
difference between a dry weight of the item and a wet weight of the
item and dividing the difference by a density of the first
fluid.
23. The system of claim 17, wherein the display is further
configured to display a user interface requesting a user input
indicating a quantity of at least one item type, wherein the dry
weight is associated with the item type.
24. The system of claim 17, wherein at least one of the first and
second display elements in the graphical representation of the
container comprises a user-manipulable sliding marker.
25. The system of claim 17, wherein the graphical representation is
generally triangular, and the first display element corresponds to
a volume of amniotic fluid, and the second display element
corresponds to a volume of blood.
26. The system of claim 17, wherein the display is further
configured to display the estimated quantity of the first fluid on
the display.
27. The system of claim 17, wherein the quantity of the first fluid
comprises a volume of the first fluid.
28. The system of claim 17, wherein the quantity of the first fluid
comprises a volumetric rate of loss of the first fluid.
29. The system of claim 17, wherein the display is configured to
alert a user if the estimated quantity of the first fluid meets a
predetermined threshold.
30. The system of claim 17, further comprising an optical sensor
coupled to the processor.
31. The system of claim 17, wherein the processor is further
configured to estimate a number of weighed items based at least in
part on an aggregate weight of one or more weighed items of an item
type, and a dry weight associated with the item type.
32. The system of claim 17, wherein the processor is configured to
estimate the quantity of the first fluid further based at least in
part on an estimated third volume of the first fluid.
33. The system of claim 17, wherein the display is configured to
display a third display element for receiving a third user input
indicating the estimated third volume of the first fluid in a
second container.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority to U.S. Patent Application
Ser. No. 62/446,333 filed on Jan. 13, 2017, which is hereby
incorporated by this reference in its entirety.
TECHNICAL FIELD
[0002] This invention relates generally to the field of tracking
fluid loss, and more specifically to new and useful systems and
methods for estimating blood loss during a medical procedure.
BACKGROUND
[0003] Inaccurate estimation of fluid loss (e.g., blood) from a
patient, such as during a medical procedure, may put the patient's
health at risk. For example, accurate measurement of blood lost by
a mother after childbirth may help quickly diagnose a
life-threatening instance of postpartum hemorrhage, which is a
leading cause of maternal mortality. Underestimation of patient
blood loss may lead to delayed resuscitation and transfusion,
increased risk of infections, tissue death, or even patient death,
such as in the event of hemorrhage. Furthermore, overestimation of
patient blood loss may result in the unnecessary consumption of
transfusion-grade blood, and may lead to shortages of
transfusion-grade blood that is needed for other patients.
[0004] Furthermore, inaccurate estimation may be a significant
contributor to high operating and medical costs for hospitals,
clinics, and other medical facilities. For example, unnecessary
blood transfusions, resulting from overestimation of patient blood
loss, may lead to higher operating costs for medical institutions.
Additionally, delayed blood transfusions, resulting from
underestimation of patient blood loss, have been associated with
billions of dollars in avoidable patient infections and
re-hospitalizations annually. Thus, it is desirable to have more
accurate systems and methods for characterizing fluids from a
patient.
SUMMARY
[0005] Generally, in one variation of a computer-implemented method
for quantifying fluid loss from a patient, the method includes
estimating a first volume of a first fluid (e.g., blood) contained
in at least one item, displaying a graphical representation of a
container with user inputs on a display, estimating the second
volume of the first fluid in the container based at least in part
on at least one of the user inputs, and estimating a quantity
(e.g., volume, volumetric rate of loss) of the first fluid based at
least in part on the estimated first and second volumes of the
first fluid. The at least one item containing the first volume of
the first fluid may include, for example, a surgical textile or a
canister. The first volume of fluid may be estimated based on a
difference between a dry weight of the item and a measured wet
weight of the item when the item contains the first volume of the
first fluid. Additionally, in some variations, the first volume of
fluid may be estimated by dividing the difference between dry and
wet weights of the item by a density of the first fluid.
Furthermore, the graphical representation may include a first
display element for receiving a first user input indicating the
volume of the second fluid in the container, and a second display
element for receiving a second user input indicating a total fluid
volume in the container, where the second volume of the first fluid
in the container may be based on at least one of the first and
second user inputs. Additional volumes of the first fluid (e.g.,
collected in at least a second item, further collected to the same
container or another container) may be estimated in similar
manners. For example, the method may, in some variations, include
estimating a quantity of the first fluid further based at least in
part on an estimated third volume of the first fluid in a second
container (e.g., a canister) as detected based on image processing
techniques, weighing of the second container, user input received
by a third display element, etc. In some variations, the method may
include updating the estimated quantity of the first fluid to
include the additional estimated volumes of the first fluid.
Furthermore, an alert or alarm to the user may be provided, for
example, if the total estimated quantity of the first fluid meets a
predetermined threshold (e.g., indicating excessive or dangerous
volume of blood lost or volumetric rate of blood lost).
[0006] In some variations, the method may include identifying a
weighing event corresponding to the item being placed on a scale
and receiving the wet weight in response to identifying the
weighing event. A weighing event may be identified, for example,
based on detection of a weight measurement meeting a predetermined
threshold value and/or detecting a stable weight measurement for at
least a predetermined period of time.
[0007] The method may include displaying a graphical user
interface, including the graphical representation of the container
and its display elements. For example, the graphical user interface
may include a display prompting the user to input a quantity and/or
type of item being weighed. The method may include receiving such
user input and receiving a dry weight associated with the item
type. In one exemplary variation, the method may include displaying
a graphical representation of a container that is generally
triangular (e.g., representing a V-shaped blood collection drape).
In this exemplary variation, the graphical representation may
include one display element corresponding to a volume of amniotic
fluid, and another display element corresponding to a volume of
blood. The display elements may be user-manipulable sliding
markers, or other suitable elements for receiving user input of one
or more fluid volumes.
[0008] In some variations, the method may further include receiving
an aggregate weight of one or more weighed items of an item type
and estimating a number of weighed items based at least in part on
the aggregate weight and a dry weight associated with the item
type. This may, for example, help facilitate counting and tracking
of items (e.g., surgical sponges or other substrates described
herein) used during the medical procedure, such as for reducing
risk of inadvertent foreign object retention in the patient.
[0009] Generally, in one variation of a system for quantifying
fluid from a patient, the system includes a wireless scale
configured to measure a wet weight of at least one item containing
a first volume of a first fluid, a display configured to display a
graphical representation of a container containing a volume of a
second fluid and a second volume of the first fluid, and a
processor coupled to the wireless scale and the display. The
graphical representation may include a first display element for
receiving a first user input indicating the volume of the second
fluid in the container and a second display element for receiving a
second user input indicating a total fluid volume in the container.
The processor may be configured to estimate the first volume of the
first fluid in the item based on a difference between a dry weight
of the item and a set weight of the item, estimate the second
volume of the first fluid in the container based on at least one of
the first and second user inputs, and estimate a quantity of the
first fluid based at least in part on the estimated first and
second volumes of the first fluid. The system may further include
an optical sensor. In some variations of the system, the processor
may be configured to perform one or more various aspects of the
methods described above.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIG. 1 is an illustrative schematic of one variation of a
system for quantifying fluid from a patient.
[0011] FIG. 2 is an illustrative flowchart schematic of one
variation of a method for quantifying fluid from a patient.
[0012] FIG. 3 is an exemplary user interface prompting a user input
of a quantity of one or more items, such as for weighing.
[0013] FIG. 4 is an exemplary user interface displaying an
estimated quantity of a volume of fluid contained in a weighed
item.
[0014] FIG. 5A is an exemplary user interface displaying a
graphical representation of a container and display elements for
user inputs.
[0015] FIG. 5B is another exemplary user interface displaying a
graphical representation of a container and display elements for
user inputs.
[0016] FIG. 6 is an exemplary user interface displaying estimated
quantities of a fluid.
[0017] FIG. 7 is another exemplary variation of a user interface
displaying a graphical representation of a container and display
elements for user inputs.
[0018] FIG. 8 is an illustrative schematic of another variation of
a system for quantifying fluid from a patient.
[0019] FIG. 9 is another exemplary variation of a user interface
displaying estimated quantities of a fluid.
DETAILED DESCRIPTION
[0020] Examples of various aspects and variations of the invention
are described herein and illustrated in the accompanying drawings.
The following description is not intended to limit the invention to
these embodiments, but rather to enable a person skilled in the art
to make and use this invention.
[0021] Overview
[0022] Generally, the methods and systems described herein may be
used to quantify fluids that are lost by a patient during a medical
procedure (e.g., labor and delivery, surgical procedure, etc.). For
example, the methods and systems may be used to track or otherwise
estimate a quantity of fluid (e.g., blood) lost by a patient
throughout a medical procedure, and the estimates may be updated
and displayed in substantially real-time during the procedure
and/or at the conclusion of the procedure. In some variations,
estimated quantities of a fluid of interest from multiple sources
may be aggregated to generate an estimate of total loss of the
fluid. Additionally or alternatively, at least some
fluid-collecting items (e.g., surgical textiles) may be tracked and
accounted for via weighing and/or counting, such as for reducing
the risk of inadvertently retaining foreign objects in the
patient.
[0023] For example, during a medical procedure, extracorporeal
fluids (e.g., blood) that are lost by the patient may be collected
with surgical textiles or other absorbent items, such as surgical
sponges (e.g., laparotomy sponges), surgical dressings, surgical
gauze, surgical towels, absorbent pads or drapes (e.g., chux pads),
vaginal packs and/or other textiles or absorbent items, etc.
Textiles or absorbent items may be placed in a bag (e.g., sponge
count bag) for tracking purposes, hygienic purposes, etc.
Additionally or alternatively, extracorporeal fluids that are lost
by the patient may be collected in a container, such as a canister.
Some applications of the methods and systems may involve collection
of lost fluids with a specialized container. For example, during
labor and delivery procedures, a drape with at least one pocket
(e.g., a blood collection drape with a triangular pocket) may be
placed under the patient for collecting blood, amniotic fluid,
urine, etc. The quantity of fluid collected in at least some types
of items, such as surgical textiles and/or canisters, may be
estimated based on a measured weight (mass) of the item when
containing fluid. In some variations, multiple batches of such
items may be weighed (e.g., as each batch of one or more textiles
become saturated) and aggregated into a running total or overall
estimate of the quantity of fluid lost by the patient during the
procedure. Such estimates may, in some variations, be combined with
estimates of fluid collected in batches and/or cumulatively over
time in some other types of items, such as canisters or blood
collection drapes. For example, total volume of fluid and/or total
rate of fluid loss may be estimated at any particular point during
the procedure and/or post-procedure.
[0024] The methods and systems described herein may be used in a
variety of settings, including in a hospital or clinic setting
(e.g., operating or clinic setting), a military setting (e.g.,
battlefield) or other suitable medical treatment settings. This
information can be used to improve medical treatment of patients,
as well as reduce costs to medical institutions and patients. For
example, medical practitioners (e.g., nurses, surgeons) who receive
this information during and/or after a medical procedure may be
able to make more appropriate decisions for treatment of the
patient (such as determining whether to provide a blood transfusion
to the patient and how much blood is necessary) based on more
accurate information on patient status. With more accurate
information on the patient's fluid loss, practitioners may be able
to, for example, avoid providing unnecessary blood transfusions
(which deplete inventory and increase risk of complications due to
transfusions), while also avoiding delayed blood transfusions
(which risk patient health).
[0025] The methods described herein may be computer-implemented and
performed at least in part by one or more processors. For example,
as shown in FIG. 1, in one variation, the method may be performed
at least in part by a computer device such as a mobile device 150
(e.g., tablet, smartphone, etc.) in a delivery room, an operating
room, or other medical site. However, some or all of the method may
be performed by one or more processors that are separate from the
mobile device 150 (e.g., on-site in the room or remotely outside
the room). Other aspects of variations of methods and systems for
quantifying fluids from a patient are described in further detail
herein.
Methods for Quantifying Fluids
[0026] As shown in FIG. 2, in some variations, a
computer-implemented method 200 for quantifying fluids from a
patient may include estimating the first volume of a first fluid
based on a difference between a wet weight and a dry weight of the
item 230. The method may further include receiving a wet weight of
at least one item 210 containing a first volume of a first fluid,
receiving a quantity of at least one item type 220, receiving a dry
weight of the item type 222, such that the received wet weight and
dry weight may be used to estimate the first volume of the first
fluid. The method 200 may further include displaying a graphical
representation of a container 240 containing a volume of a second
fluid and a second volume of the first fluid, receiving a first
user input 250 indicating the volume of the second fluid in the
container, receiving a second user input 252 indicating a total
fluid volume in the container, and estimating the second volume of
the first fluid 260 based on at least one of the first and second
user inputs. Furthermore, the method 200 may include estimating a
quantity of the first fluid 280 based at least in part on the
estimated first and second volumes of the first fluid, and may
include displaying the estimated quantity of the first fluid 290.
Estimates of fluid collected via other sources (estimates generated
by weighing and/or received through user input) may additionally or
alternatively be used to quantify fluid from the patient, as
further described herein.
[0027] For example, in one exemplary variation, the method may be
used to quantify blood from a patient undergoing a labor and
delivery procedure. Some of the blood lost by the patient may be
collected with one or more types of surgical textiles or other
substrates, and the quantity of blood in these substrates may be
estimated based on weight of the substrates. Additionally or
alternatively, some of the blood lost by the patient may be
collected and estimated with a blood collection drape (e.g.,
collecting from underneath the patient) and/or a canister (e.g.,
collected via suction wand, etc.). Estimates of blood from the
weighed items and the other fluid-collecting items may be displayed
separately (e.g., according to each fluid-collecting item) and/or
may be summed and displayed as an aggregate estimate of blood lost
by the patient.
Weighed Fluid-Collecting Items
[0028] As described above, some items or other substrates may be
used to soak or collect fluids lost by a patient. The amount of
fluid collected in each item may generally be estimated using a
difference between the wet weight of the item (the weight of the
item including the fluid to be estimated) and a dry weight of the
item (the weight of the item without any fluid). Accordingly, in
some variations, the method may include receiving a wet weight of
at least one item 210 and receiving a dry weight of the item (as
further described below).
[0029] For example, as shown in FIG. 1, the wet weight of the item
may be measured with a scale 110 and communicated to a processor
such as a processor 154 in a mobile device 150. Before the scale
measures the wet weight of the item, the scale may first be tared
or zeroed in order to set a baseline reference value relative to
which the wet weight is determined. In some variations, the scale
may be tared while no fluid-collecting items are placed on the
scale, such that the baseline reference value may incorporate
substantially no pre-existing weight placed on the scale or may
incorporate a substantially empty receptacle (e.g., bucket 120)
configured to receive fluid-collecting items. For example, each
batch or multiple batches of fluid-collecting items may be
separately weighed and analyzed, then removed prior to the
placement of a subsequent batch on the scale. Alternatively, the
scale may be tared while one or more previously-analyzed batches of
items are placed on the scale, such that only the weight of an
additional, subsequent batch of items is used and analyzed for
fluid content in the additional batch.
[0030] In some variations, taring may be triggered by a user with a
user interface that is configured to remotely communicate a tare
action to the scale. Such remote taring may be triggered, for
example, by tactilely interacting with a displayed user interface
(e.g., on a touchscreen on a mobile device 150 or other device), by
voice command, foot pedal, or any other suitable user interface.
Additionally or alternatively, taring may be triggered by the user
pressing a button or other element located on the scale itself. In
yet other variations, the method may include automatically taring
the scale based on one or more conditions. In one variation, the
method may include detecting a predetermined type or sequence of
events and taring the scale in response to detecting the
predetermined type or sequence of events. For example, in response
to detecting that a batch of fluid-collecting items has been placed
on the scale or weighed and analyzed (as indicated, for example, by
user input via a user interface), and subsequently removed (as
indicated, for example, by a sudden decrement in measured weight on
the scale), the method may include automatically taring the scale
to prepare the weighing and analysis of the next batch of
fluid-collecting items. In another variation, taring may
automatically occur after a predetermined length of time (e.g., ten
seconds, thirty seconds, one minute, five minutes, etc.) without
any significant change in detected weight on the scale. In yet
another variation, taring may automatically occur whenever a
negative weight is measured. For example, taring may automatically
occur if a negative weight is measured for a period of time equal
to or exceeding a predetermined amount of time, such as at least
about 0.5 seconds, at least about 1 second, at least about 2
seconds, at least about 5 seconds, etc.
[0031] Following taring of the scale, as shown in FIG. 1, the user
may place a batch including at least one item 112 containing fluid
114 (e.g., a surgical textile at least partially saturated with
blood) in a receptacle 120 on a scale 110 (or alternatively,
directly on the scale 110), which measures the wet weight of the
item 112. Generally, the scale 110 may communicate the measured wet
weight (wirelessly and/or via a wired connection) to a processor
that receives the wet weight value for analysis as described
elsewhere herein.
[0032] In some variations, as shown in FIG. 2A, the method may
include identifying a weighing event 208 and receiving the wet
weight of the item 210 in response to detecting the weighing event.
Generally, a weighing event may correspond to placement of at least
one fluid-collecting item on the scale. For example, a weighing
event may be determined based on detection of an increase in
measured weight beyond a predetermined weight threshold. For
example, the predetermined weight threshold may be a value ranging
between about 5 grams and about 15 grams, between about 7 grams and
about 13 grams, or about 10 grams, etc.). In some variations, the
predetermined weight threshold may differ depending on the type of
item being measured (e.g., which may be known based on user input,
as described below, and entered by the user before the user places
the batch of items for weighing on the scale). For example, the
predetermined weight threshold may be similar in value to a dry
weight of a user-selected item type, or expected combined dry
weight of multiple items of one or more user-selected item
types.
[0033] In some variations, the predetermined weight threshold may
be determined based at least in part on one or more previously
measured dry weights of one or more items, where the measured dry
weights are stored in memory as further described below. For
example, the predetermined weight threshold may be based at least
in part on the lowest of one or more previously measured and stored
dry weights of an item. In one illustrative example, the
predetermined weight threshold may be equal to the lowest of all
previously measured and stored dry weights (e.g., of all weighed
items, of all weighed items of the same type as the item currently
being measured, etc.) or a fraction of such lowest dry item weight
(e.g., the lowest previously measured and recorded dry weight
multiplied by a scaling factor such as a factor between about 0.1
and about 0.9, between about 0.25 and about 0.75, about 0.5, etc.).
In some of these variations, all or only a subset of previously
measured and stored dry item weights may be used when determining
the lowest stored dry item weight. For example, the predetermined
weight threshold may be equal to the lowest dry item weight out of
the preceding 5, 10, 15, 20 (or other suitable number) measurements
performed and stored, or a fraction of such lowest dry item weight.
As another example, the predetermined weight threshold may be equal
to the lowest dry item weight out of all measurements performed and
stored in the preceding 10 minutes, 30 minutes, 1 hour, 2 hours (or
other suitable time period), or a fraction of such lowest dry item
weight.
[0034] Furthermore, the method may include responding differently
to different predetermined weight thresholds in order to identify
whether a weighing event has occurred. For example, if a measured
weight is below a first, lower weight threshold value (e.g., about
2 grams), then no response action may be taken. If a measured
weight is above a second, higher weight threshold (e.g., about 10
grams), then the measured weight may be considered a wet weight
corresponding to a weighing event. If a measured weight is between
the lower weight threshold value and the higher weight threshold
value, then the method may include prompting the user to confirm
whether a weighing event has occurred.
[0035] Additionally or alternatively, a weighing event may be
determined based on detection of a stable measurement reading
(e.g., substantially no fluctuation in measured weight, such as
fluctuation only within a predetermined measurement range) for a
predetermined threshold of time. For example, the predetermined
measurement range may be about .+-.0.1 grams, .+-.0.07 grams,
.+-.0.05 grams, .+-.0.02 grams, .+-.0.01 grams, etc., and the
predetermined threshold of time may range between about 1 second
and 5 seconds, between about 2 second and 4 seconds, etc.
Combinations of various suitable conditions (e.g., detecting a
threshold weight value for at least a predetermined period of time)
may be used to identify a weighing event.
[0036] As yet another example, a weighing event may be determined
based on user input, such as a user interacting with a user
interface (e.g., buttons on the scale, user-manipulable or
touch-sensitive icons on a displayed user interface, voice
commands, etc.) to confirm the existence of a weighing event.
[0037] Furthermore, in some variations, the method may include
applying a machine learning algorithm to distinguish between
fluctuations in weight measurements due to weighing events (e.g.,
due to placement of at least one fluid-collecting item on the
scale) and those due to non-weighing events, such as fluctuations
caused by repositioning of a receptacle on the scale, fluctuations
caused by shaking of a surface on which the scale rests, and/or
fluctuations caused by vibrations when personnel walks near the
scale or when machinery or equipment is operated near the scale,
etc. For example, a training data set of scale measurement signals
may be generated based on signals gathered during known weighing
events and known non-weighing events, and a machine learning
algorithm (e.g., data clustering algorithm, etc.) may be trained
using the training data set and subsequently applied to identify
when a scale signal pattern is associated with a weighing event or
one or more types of non-weighing events. Additionally or
alternatively, in some variations, a signal processing algorithm
may be applied to time-based signals. For example, frequency domain
transforms (e.g., Fourier transforms, etc.) may be applied to the
scale signal after intervals of 0.5 seconds, 1 second, 2 seconds,
or 5 seconds, etc., to determine the frequency of a signal
variation. This interval may be shortened or lengthened based on
one or more various factors or conditions, such as an
identification of another weighing event as described above (e.g.,
the difference in stabilized weight crossing a particular threshold
to recognize a weighing event). The determined frequency of signal
variation may then be applied to a learned model (e.g.,
classification model) to recognize whether the frequency is best
matched to one or more particular pre-learned non-weighing events
such as a person walking by, other objects being placed on the same
surface as the scale (but not in the scale), nearby machinery, etc.
Additionally, low-pass/high pass filtering techniques may be used
to smooth out the scale signal over a given period of time to aid
in signal processing. These filters may, for example, be forward
looking only, backward looking only, or some permutation of
directionality in order to perform appropriate smoothing.
Furthermore, recognition or identification of a weighing event or a
non-weighing event may, in some variations, be determined using a
suitable combination of frequency domain and signal
smoothing/filtering techniques.
[0038] The method includes receiving a wet weight of the item 210,
which may be in response to detecting the weighing event. For
example, the scale may be pinged or prompted to communicate a
weight measurement. As another example, the scale may
substantially, continuously, or periodically communicate its weight
measurement (e.g., every 0.05 seconds, 0.1 seconds, 0.5 seconds or
every 1 second) and only a weight measurement following detection
of the weighing event may be taken as a wet weight of the item and
used for subsequent analysis as described elsewhere herein. In some
variations, the wet weight of the item may be based on a single
measurement value, or may be based on multiple measurement values
(e.g., average) taken around the time of the weighing event. Upon
receiving the wet weight of the item, the method may include
storing the wet weight value in memory or another suitable data
storage device.
[0039] The method may further include receiving a quantity of at
least one item type 220 in the batch of weighed fluid-collecting
items. The received quantity of item types may be used at least in
part to determine total dry weight of all items being weighed in a
particular batch. Although FIG. 2 shows that receiving a quantity
of at least one item type 220 may be performed following receiving
a wet weight of the at least one item 210, it should be understood
that in other variations, receiving a quantity of at least one item
type 220 may be performed prior to or substantially concurrently
with receiving a wet weight of the least one item 210.
[0040] As shown in FIG. 3, in some variations, a user interface may
prompt a user to enter quantity of each item or other substrate
being weighed. Various item types may be displayed for selection by
the user, such as surgical sponges (e.g., laparotomy sponges),
surgical dressings, surgical gauze, surgical towels, absorbent pads
or drapes (e.g., chux pads), vaginal packs and/or other textiles or
absorbent items, etc. Additionally or alternatively, one or more
types of containers holding any such textiles or other absorbent
items (e.g., sponge count bag) may be displayed. Furthermore, the
items may be biological (e.g., clot structure including fluid to be
measured). Additionally, different sizes and/or brands of items
(e.g., containers or other surgical item or substrate described
herein) may be displayed for selection by the user. In some
variations, the user interface may enable a user to enter a custom
item type or other substrate not already presented as an option for
selection, such as by providing a space for typing in an item type
name and a dry weight associated with the item type and known by
the user. Additionally or alternatively, the user may empirically
determine and/or confirm a dry weight for an item or other
substrate (e.g., custom item type) using the scale. For example,
the user may weigh one or more dry samples of an item type of
sufficient quantity so as to provide a statistical confidence as to
the dry weight of a single sample of the item type. A dry weight of
the item type may be estimated as the average dry weight for a
single sample of the item type, based on the total weight and
number of dry samples. Accordingly, the user interface may, for
example, prompt the user to weigh at least a minimum number of dry
samples of a new item type, prompt the user to input the quantity
of dry samples of the new item type, measure the total weight of
the dry samples, determine average dry weight of a single dry
sample, prompt the user to input a custom item type name for the
new item type, and store in memory (or any suitable data storage
device) the average dry weight of a single dry sample as associated
with the custom item type. The custom item type may be displayed
for selection by the user during a medical procedure.
[0041] In one variation, as shown in FIG. 3, the item types may be
presented in an array in combination with item counters. The item
types may be identified, for example, with word labels and/or
representative images or graphics (e.g., image of a type of
unsaturated surgical textile may represent surgical textiles of
that type). The item counters may be incremented and/or decremented
by the user (e.g., by touching designated icons for incrementing
and/or decrementing) to indicate the quantity of each type of item
being weighed. Alternatively, the item types may be listed in
drop-down menus or presented for selection in any suitable manner.
Furthermore, in addition or alternative to displaying item counters
to indicate quantity, the user interface may display a text box
prompting the user to manually type in a quantity of item type,
display a user-rotatable numbered dial, or facilitate user input of
quantity of one or more item types in any suitable manner. Upon
input of the quantity of item types, the user may confirm the
selection (e.g., by selecting a displayed "analyze" icon as shown
in FIG. 3, or any suitable icon).
[0042] The method may, in some variations, include storing and
displaying a subset of selectable item types under certain
circumstances. For example, the method may include storing selected
types of items as "favorites" or "preferred item types", etc., such
as selected types for particular kinds of medical procedures (e.g.,
chux for labor and delivery), selected brands for particular
medical institutions (e.g., where a hospital may stock only a
particular brand of an item type), etc. Furthermore, during a
medical procedure with multiple batches of items for weighing, the
method may include automatically suggesting items types during the
procedure, such as based on item types previously selected during
the same procedure or in previous procedures of the same procedure
type. Storing and displaying a subset of selectable item types
under certain circumstances may, for example, reduce time needed
for the user to input quantities of one or more item types.
[0043] In yet other variations, the method may include using
computer vision techniques to estimate or predict the quantity
and/or item types being weighed. For example, the method may
include generating or receiving an optical image of the items on
the scale (e.g., on a bucket or tray on the scale), and a
classification algorithm, etc. may be applied to the image data for
determining a number and/or type of items on the scale. As another
example, the method may include using an infrared (IR)
depth-sending camera to perform a 3D scan of the items on the scale
and determine contours of the items present on the scale. The
method may include applying a classification algorithm to classify
the batch of items on the scale as including a particular number of
items and/or item type. The classification algorithm may, for
example, base its classification on contour features of piles or
collections of textiles known to include zero, one, two, etc. items
of particular item types. The predicted quantity and/or item types
being weighed may, in some variations, be confirmed by a user
before being used in subsequent analysis.
[0044] Based on the quantity of the at least one item type being
weighed, the method may include receiving a dry weight of the at
least one item type 222. The dry weight for a single instance of
each item type may, for example, be stored in memory or other
suitable data storage device, as part of a look-up table, hash
function, etc. such that the dry weight may be retrieved or
received upon knowing the type or types of items that have been
weighed. A total dry weight of multiple items may be determined by,
for example, multiplying the dry weight of a single instance of an
item type by the quantity of the item type to achieve a subtotal
dry weight of each item type, then summing the subtotal dry weights
of multiple item types to determine the total dry weight.
[0045] Additionally or alternatively, in some variations, the
method may include weighing one or more items before being used to
collect fluid. For example, weighing the one or more items may
directly generate dry weight values of the items (e.g., instead of
receiving the values from a stored memory, or to confirm the values
received from a stored memory). Each individual item may be
separately weighed, or groups of items of the same type may be
weighed (whereupon collective weight may be divided by the number
of items to estimate the dry weight of a single instance of that
item type).
[0046] In some variations, weighing the one or more items and/or
receiving a quantity of item types may be used to help track
surgical items (e.g., textiles) used in a medical procedure. For
example, surgical textiles may, during a medical procedure, be
placed inside a patient to absorb blood and be subsequently removed
(e.g., upon saturation or after the procedure is complete).
However, there is a risk that at least some textiles may be
inadvertently retained inside the patient, which may harm patient
health such as by causing infection or even death. One approach to
reduce the retention of foreign objects in a patient is to perform
a count before and after (or throughout) the procedure, and make
sure that the "before" and "after" counts are equal such that all
objects are accounted for. For example, in one variation, weighing
the one or more items may be used to help facilitate an accurate
pre-procedural "before" count of items (e.g., textiles). Such a
"before" count may be performed, for example, by receiving an item
type to be counted (e.g., based on user input, machine vision
techniques if the item is in the field of view of an image sensor,
etc.), measuring a total weight of a batch of one or more dry or
unused items of the item type, and dividing the total weight by a
known dry weight of the item type. Furthermore, receiving a
quantity of item types of items being weighed (e.g., after the
fluid-collecting items are removed from the patient) may be help
facilitate an accurate "after" count of used items throughout
and/or after the procedure. Such "before" and "after" item counts
may be compared to help reduce the risk of inadvertent foreign
object retention in the patient, which may be harmful to the
patient. A discrepancy in the "before" and "after" counts may
prompt medical staff to locate any apparently missing textiles or
other items, perform a recount, perform an X-ray scan of the
patient, or perform other risk mitigation. Additionally or
alternatively, a complementary "after" count of dry or unused items
may be performed in a manner similar to that described for
performing a "before" count, by receiving an item type, measuring
total weight of dry or unused items that that are left over after
the procedure, and dividing the total weight by a known dry weight
of the item type. In one illustrative example of how to use the
complementary "after" count of dry or unused items, a discrepancy
between the "before" count compared to the sum of the "after" count
of used items and the complementary "after" count of unused items
may prompt medical staff to perform risk mitigation (e.g.,
searching for apparently missing items, recounting, performing an
X-ray scan of the patient, etc.).
[0047] Furthermore, weighing the one or more items may help
facilitate an accurate count of items to be used during the medical
procedure in view of potential mispackaging or erroneous manual
counting, etc. For example, an unused pack or collection of
surgical textiles of the same type has an expected total dry weight
given the number of textiles (e.g., ten) and a known dry weight of
an individual textile of that type. However, if the pack of
textiles is weighed and its total weight deviates significantly
from the expected total dry weight, it may signify that the pack of
textiles has been mispackaged or mislabeled, and may indicate that
more or fewer textiles than expected are included in the pack.
Accordingly, if the actual weight is sufficiently different from
the expected weight (e.g., is greater than or less than at least
half the known dry weight of an individual textile of that type),
then the method may include alerting the user to review, recount,
or otherwise reassess the number of textiles in the pack.
[0048] Upon receiving both the wet and dry weights of the item (or
items) containing a first volume of a first fluid, the method may
include estimating a first volume of the first fluid 230 based on a
difference between the wet weight and the dry weight of the item.
Furthermore, the method may, in some variations, include dividing
the difference between the wet weight (mass) and the dry weight
(mass) of the item or items by the density of the fluid, in
accordance with Equation 1 below:
volume of fluid in item = wet weight of item - dry weight of item
density of fluid ( 1 ) ##EQU00001##
[0049] For example, in one variation, the method may be used to
estimate a volume of blood, which has a density of about 1.06 g/ml.
Accordingly, to estimate a volume of blood in a weighed item, the
method may include dividing the difference between the item's wet
weight and dry weight (expressed in grams) by 1.06 g/ml, resulting
in an estimate of the volume of blood expressed in milliliters.
[0050] In some variations in which the method is used to estimate a
volume of a fluid which has a density of roughly 1.0 g/ml, the
difference between the wet weight and the dry weight in grams may,
in some applications, provide a sufficient estimate of volume of
fluid in the weight items and the step of dividing the difference
in wet and dry weights by the density of fluid may be omitted. For
example, the step of dividing by the fluid density may be omitted
if only a rough estimate of blood is required (since blood has a
density generally approximating 1.0 g/ml), or a volume of urine or
other fluid with a density of about 1.0 g/ml is being estimated in
the weighed items.
[0051] In other variations, the difference between wet and dry
weights in units of force (e.g., Newtons) may be used to estimate
volume of fluid, such as by compensating for acceleration of
gravity (e.g., 9.8 m/s.sup.2) in Equation 1.
[0052] The method may include displaying the estimated volume of
fluid to the user. For example, as shown in FIG. 4, the method may
include displaying on a user interface a quantified blood loss
(QBL) that has collected in a weighed batch of items containing
blood. The method may further include displaying the quantity and
item types of items that contain the volume of blood, which may,
for example, help confirm to the user the correct number and item
type were used to determine the dry weight value used in the
analysis. The quantity and item type may, for example, be displayed
as words as shown in FIG. 4, but additionally or alternatively may
be displayed with representative graphics or images.
[0053] Although in some variations, the method may additionally or
alternatively include weighing and analyzing items (e.g., textiles,
etc.) that collect fluids by soaking or absorbing fluids, in some
variations, the method may additionally or alternatively include
weighing or analyzing items (e.g., V-shaped blood collection drape,
canister) that collect fluids in a receptacle. For example, a
volume of fluid collected in a container may be estimated in a
process similar to that described above. A container may be
associated with a first weight (e.g., an empty weight, dry weight,
or other baseline reference weight such as weight of the container
including an amount of fluid previously estimated), then weighed to
determine a second weight (e.g., a wet weight or other measurement
weight to be compared to the baseline reference weight). The
difference between the first and second weights may be divided by
the density of the fluid to estimate a volume of fluid in the
container (or additional volume of fluid since the previous
estimation). This estimate of fluid in the container may, for
example, be used to confirm or corroborate other estimations of
volume (e.g., those based on reference markers on the
container).
Other Fluid-Collecting Items
[0054] As described above, some containers or other receptacles may
be used to collect fluids lost by a patient. For example, a
V-shaped blood collection drape (e.g., for labor and delivery
applications of the method) or a canister may collect fluids
without soaking or absorbing the fluid. When a fluid of interest
(e.g., blood) is collected in one or more such containers,
estimates of the fluid in the containers may be combined with
estimates of the fluid in the weighed items (e.g., estimated as
described above) to generate an aggregate total of volume of the
fluid lost by the patient.
[0055] In some variations, a fluid of interest (e.g., blood) may be
collected in a container in combination with one or more other
secondary fluids of interest. Where the different fluids have
different densities and are substantially immiscible, the different
fluids may separate into different layers within the container,
such that a total volume of fluid in the container may include at
least a first layer portion including one fluid and a second layer
portion including another fluid. For example, as shown in the
illustrative schematic of FIG. 1, a container 130 may include total
fluid volume 136 that includes a volume of a second fluid 132 and a
volume of a fluid of interest 134. Furthermore, the container may
include markings (e.g., graduated or calibrated markings) to
facilitate estimation of fluid volumes. For example, in a labor and
delivery procedure, both blood and amniotic fluid may be collected
in a V-shaped blood collection drape placed underneath the patient.
Accordingly, as shown in FIG. 2, in one variation, the method may
include displaying a graphical representation of a container 240
containing a volume of a second fluid and a second volume of a
first fluid of interest. The graphical representation of the
container may include one or more display elements for receiving
one or more user inputs indicating a volume of one or more of the
fluids contained in the container.
[0056] FIG. 5A shows an exemplary graphical representation 510 of a
V-shaped blood collection drape container. The graphical
representation 510 may be generally triangular to mimic the
structure of the V-shaped blood collection drape. The graphical
representation may include a first display element 520 for
receiving a first user input indicating the volume of the second
fluid in the container and a second display element 530 for
receiving a second user input indicating a total fluid volume
(e.g., including the volume of the second fluid and the volume of
the fluid of interest) in the container. The first and second
display elements may directly correlate to fluid levels in the
container itself (e.g., which may be estimated using fluid
measurement markings on the container), such that the user need not
perform mental calculations to estimate a separate volume of every
individual type of fluid, thereby reducing inaccuracies in fluid
loss estimations resulting from human error. Furthermore, the
graphical representation may include additional display elements
for receiving user inputs indicating additional volumes of fluid
(e.g., a third display element for indicating volume of a third
fluid, etc.). For example, as shown in FIG. 5B, the graphical
representation 510 may include a third display element 540 for
receiving a third user input indicating a volume of a third
fluid.
[0057] The user input may involve manipulating the display elements
relative to displayed fluid measurement markings corresponding to
actual fluid measurement markings on the actual container, so as to
mirror the relative positions of actual fluid levels and fluid
measurement markings on the actual container. For example, the
first display element 520 may be configured to indicate a volume of
amniotic fluid (which may be estimated directly from markings on
the container), and the second display element 530 may be
configured to indicate a total volume of fluid including the
amniotic fluid and blood (which may also be estimated directly from
markings on the container). Furthermore, in variations in which a
third display element 540 is included in the graphical
representation of the container, the third display element 540 may
be configured to indicate a known volume of another fluid such as a
saline or antiseptic wash (e.g., that has been poured over the
patient's birthing area to disinfect the area). Accordingly, in
some variations, before manipulating the display elements, a user
may not be required to mentally calculate the volume of blood based
on a difference between relevant markings on the container, thereby
reducing inaccuracies in blood loss estimation.
[0058] As shown in FIG. 5A, the first and/or second display
elements 520 and 530 may include sliding markers that are
user-manipulable and movable up and down along the depth of the
graphical representation of the container. For example, when
displayed on a touch-sensitive display, the user input may be
received by a user touch on the display in which the user touches
and drags the sliding markers to desired positions, taps the
sliding markers (or increment counter elements, or selected
portions of the graphical representation of the container, etc.) to
selectively increment or decrement them to desired positions, etc.
In response to detecting the positions of the first and second
display elements 520 and 530, the method may include adjusting the
estimated fluid volumes based on the detected positions of the
first and second display elements 520 and 530 (e.g., adjusting an
estimated volume of the second fluid based on the detected position
of the first display element 520, adjusting an estimated total
fluid volume based on the detected position of the second display
element 530, etc.). The numerical volume values may be displayed
adjacent the sliding markers.
[0059] In other variations, the first and/or second display
elements 520 and 530 may additionally or alternatively have any
other suitable form for receiving user input indicating fluid
volumes. For example, in one variation as shown in FIG. 7, a
display element may include a text box 730 into which the user may
type or otherwise enter a fluid volume value.
[0060] As shown with reference to display element 540 in FIG. 5B,
in some variations, at least one of the display elements may be
locked or otherwise fixed at a particular value. For example, at
least one of the display elements may be locked at a volume value
such that an affirmative action may be required to further adjust
the volume value indicated by the display element. Any suitable
user input may initiate locking and/or unlocking of the display
element, such as a user's tap on the display element after the
display element is adjusted to the desired position,
double-tapping, selection of a separate lock button or other icon,
vocal command, etc. Additionally or alternatively, a custom
on-screen touch gesture (e.g., tracing of a circle, dual or triple
finger swipe or slide gesture, etc.) may be suitable user input for
initiating locking and/or unlocking of the display element. A
display element that is locked may be indicated with a displayed
"lock" icon 542, or any suitable indication (e.g., the word "lock",
a change in color of the display element, a change in text font in
the display element, etc.).
[0061] In other variations, only one display elements may be
displayed for receiving user input indicating a volume of fluid
contained in the container. For example, the method may include
displaying a graphical representation of a container containing
only a volume of the fluid of interest (e.g., blood). FIG. 7 shows
an exemplary graphical representation 710 of a suction canister
containing substantially only one fluid (e.g., blood that has been
collected by a suction wand). The graphical representation 710 may
be, for example, frustoconical or generally rectangular. The
graphical representation 710 may include a display element 730 for
receiving a user input indicating the volume of the fluid in the
container. Similar to the display elements 520 and 530 described
above, in some variations, the display element 730 may include a
sliding marker that directly corresponds to a fluid level in the
container itself that may be estimated using fluid measurement
markings on the container. Alternatively, as shown in FIG. 7, the
display element may include a textbox into which a user may enter a
fluid volume value.
[0062] In yet other variations, one or more fluid volumes in the
container may be estimated based on an optical image of the
container. For example, as shown in FIG. 8, one or more optical
images may be taken with a camera or other suitable optical sensor
whose field of view includes the container containing a volume of a
fluid of interest. As such, the method may include capturing a
static, single-frame image including at least a portion of the
fluid container, and/or a multi-frame video feed including multiple
static images of the fluid container. For example, static images
may be taken periodically (e.g., every ten seconds, every thirty
seconds, etc.) or upon a user-input or other trigger event. The
image can be a color image, a black and white image, a grayscale
image, an infrared image, a field of view of an optical sensor, a
fingerprint of a field of view of an optical sensor, a point cloud,
or any other suitable type of image.
[0063] One or more machine vision techniques may be used to
estimate fluid volumes in the container based on an optical image
of the container. For example, generally, estimating fluid volume
in the container may include using machine vision techniques in
identifying a container-depicting region of an image of the
container, correlating a portion of the container-depicting region
with an estimated fluid level within the container, and estimating
a volume of fluid within the container based on the estimated fluid
level. Suitable vision techniques include segmentation techniques
(e.g., edge detection, background subtraction, grab-cut algorithms,
etc.), gauging, clustering, pattern recognition, template matching,
feature extraction, descriptor extraction (e.g., extraction of
texton maps, color histograms, HOG, SIFT, MSER (maximally stable
external regions for removing blob-features from the selected
area), etc.), feature dimensionality reduction (e.g. PCA, K-Means
linear discriminant analysis, etc.), feature selection,
thresholding, positioning, color analysis, parametric regression,
non-parametric regression, unsupervised or semi-supervised
parametric or non-parametric regression, and/or any other type of
machine learning or machine vision to estimate a physical dimension
of the container and/or its fluid contents.
[0064] Furthermore, estimating fluid volume in the container may
include implementing suitable machine vision techniques to identify
fluid level markings printed (and/or embossed, adhered, etc.) on
the fluid container and identifying the fluid boundaries (e.g.,
boundary between layers of different fluids, surface of total fluid
volume, etc.) within the canister. Fluid boundaries may be
identified, for example, based on transitions in color of pixels
along the height (e.g., vertical line of pixels) along the
container-depicting image region. For example, upper and lower
boundaries of blood in a container may be identified based on
abrupt shifts between red and non-red colors along a vertical line
of pixels in the container-depicting image region. The method may
further estimate the volume of one or more fluids within the
canister based on one or more identified fluid boundaries relative
to one or more identified fluid level markings on the
container.
[0065] Another variation of estimating fluid volume in the
container using images includes using machine vision techniques to
identify a float or other reference point corresponding to a fluid
level in the container. The identified position of the float can be
used, such as by comparing the float to optical fiducials, to
estimate fluid volume.
[0066] In another variation, fluid volume in the container may be
automatically estimated based on one or more fluid level sensors.
For example, fluid level may be detected with one or more
point-level sensors that indicate whether the fluid volume in the
container is above or below a particular threshold sensing point.
As another example, fluid level may be detected with one or more
continuous-level sensors that measure the fluid level in the
container and indicates a numerical value corresponding to fluid
volume. Any suitable fluid level sensor may be used to detect fluid
volume in the container and generate a fluid level signal that
indicates the detected fluid volume. For example, capacitance level
sensors, conductive level sensors, ultrasonic level sensor, and/or
optical sensors, etc. may be appropriate as point-level and/or
continuous-level sensors.
[0067] Other examples of estimating fluid volume in a container are
described in U.S. Pat. No. 9,171,368, entitled "System and method
for estimating a quantity of a blood component in a fluid
canister," as well as U.S. patent application Ser. No. 15/154,917,
entitled "Systems and methods for assessing fluids from a patient,"
each of which is hereby incorporated in its entirety by this
reference. In other variations, the method may include any suitable
process for estimating fluid volume in the container.
Aggregation of Fluid Estimations
[0068] Following estimation of the first and second volumes of a
first fluid (e.g., fluid of interest such as blood) among weighed
fluid-collecting items and other fluid-collecting items, the method
may include estimating a quantity of the first fluid 280 based at
least in part on the estimated first and second volumes of the
first fluid. For example, the estimated quantity of the first fluid
may be an amount of loss (e.g., volume) based on a sum of the
estimated first and second volumes of the first fluid (e.g., fluid
collected in the weighed items and other non-weighed items). As
another example, the estimated quantity of the first fluid may be a
volumetric rate of loss based on a sum of the estimated first and
second volumes of the first fluid (and any other volumetric
estimates of fluid analyzed previously for the same patient) and
the duration of time over which the first fluid has been lost by
the patient. Additionally or alternatively, the method may include
generating a present fluid loss trend in the amount or rate of loss
over time (e.g., over the course of the medical procedure), and/or
generating a predicted future fluid loss trend based on the present
fluid loss trend.
[0069] The method may further include displaying the estimated
quantity of the first fluid, and/or the breakdown of individual
volumes of fluid across the different categories of
fluid-collecting items. For example, as shown in FIG. 6, an
estimated first volume of fluid in weighed items may be displayed
as a first subtotal 610, and an estimated second volume of fluid
from a container (e.g., V-shaped blood collection drape) may be
displayed as a second subtotal 612. Furthermore, an estimated total
quantity of the fluid may be displayed as a fluid loss total 630.
As another example, as shown in FIG. 9, in addition to a first
subtotal 910 and a second subtotal 912 similar that shown in FIG.
6, another estimated volume of fluid from a weighed container or
container whose contents were entered by a user or detected
automatically through machine vision techniques and/or sensors
(e.g., a blood collection drape or suction canister) may be
displayed as a third subtotal 914. More or fewer subtotal volumes
of fluid may be displayed, which may depend, for example, on the
number of individual categories of fluid-collecting items that are
considered. Furthermore, in other variations, different kinds of
subtotals may be displayed (e.g., estimates of fluid collected by
different kinds of weighed items). Additionally or alternatively,
the method may include displaying the generated present fluid loss
trend and/or predicted future fluid loss trend.
[0070] In some variations, the method may include comparing the
estimated quantity of the first fluid (or other fluid of interest)
with a predetermined threshold for lost fluid, and triggering an
alarm if the volume of first fluid meets the predetermined
threshold. The alarm may be visual (e.g., displayed on a display)
or audible over speakers, etc. In one variation, the estimated
amount of loss of the first fluid may be compared to a threshold.
For example, in a labor and delivery application of the method, if
an estimated total amount of blood lost by the patient (and which
is collected by items subsequently weighed and/or in other items)
exceeds about 500 milliliters, then an alarm may be triggered to
warn medical personnel of the possibility of patient hemorrhage
that may endanger the health and life of the patient. In another
variation, the estimated volumetric rate of loss of the first fluid
may be compared to a threshold.
[0071] In another variation, the generated present fluid loss trend
and/or predicted future fluid loss trend may be compared to one or
more representative reference data sets. A representative reference
data set may be identified from a stored database of data based on,
for example, one or more health condition or disease factors,
practice-based factors, patient type (e.g., sex, age, weight,
ethnicity, etc.), and/or other suitable patient- or
procedure-related factors. For example, a set of reference fluid
loss values may include an average, median, mode, or a range of
historical fluid loss values from a plurality of prior procedures,
each of which may or may not be the same type as the current
procedure. Based on a similarity determined between the patient's
data and the representative reference data, the method may include
triggering an alarm indicating predicted danger to the patient
(e.g., predicted excessive future blood loss). Other examples of
generating and utilizing fluid loss trends are described in U.S.
patent application Ser. No. 15/154,921, entitled "Method for
projecting blood loss of a patient during a surgery," which is
hereby incorporated in its entirety by this reference.
Systems for Quantifying Fluids
[0072] As shown in FIG. 1, a system 100 for quantifying fluid from
a patient may include a scale 110 configured to measure a wet
weight of at least one item containing a first volume of a first
fluid, a display 158 configured to display a graphical
representation of a container containing a least a second volume of
the first fluid, and a processor 154 coupled to the scale 110 and
the display 158. For example, the graphical representation may
represent a container 130 including a total fluid volume 136 that
includes a volume of a second fluid 132 and a volume of the first
fluid 134. Furthermore, as described above, in some variations, the
graphical representation may include a first display element for
receiving a first user input indicating the volume of the second
fluid in the container, and a second display element for receiving
a second user input indicating a total fluid volume in the
container. Generally, the system 100 may, in some variations, be
configured to substantially perform any of the variations of the
method 200 described in further detail above.
[0073] Some or all of the system may be in an integrated device and
placed near the patient during the medical procedure (e.g., in the
operating room or delivery room) to assess patient fluids that are
lost and collected by weighable items and/or containers. For
example, the system may at least partially include a handheld or
mobile computing device 150 (e.g., that executes a native fluid
analysis application program). Such a handheld or mobile device
may, for example, be a tablet computer, laptop computer, mobile
smartphone, etc. which may include a camera, processor, and
display. However, in other variations, some or all of the system
components may be separated as discrete, interconnected devices.
For example, the camera and/or display may be located substantially
near the patient during the procedure, while the processor may be
located at a remote location (e.g., in the operating room or
delivery room separate from camera and/or display, or outside the
operating room or delivery room), communicating with the camera and
display through a wired or wireless connection or other
network.
[0074] The scale 110 may be an electronic or digital scale having
suitable range and resolution for measuring medical or surgical
items containing fluid. For example, the scale may be configured to
measure loads up to a maximum load ranging between about 100 grams
and 10,000 grams, between about 250 grams and 750 grams, at least
about 500 grams, etc. The scale may further be configured to
measure loads with a precision of at least 0.01 grams, at least 0.1
grams, at least 1 gram, etc. In some variations, the scale 110 may
be wireless (e.g., communicating with Bluetooth or other suitable
communication protocol) and configured to communicate with the
processor 154 remotely. Additionally or alternatively, the scale
110 may be configured to communicate with the processor 154 via a
wired connection. Wireless or wired communication status may be
indicated to the user. For example, confirmation of functional
communication between the scale 110 and the processor 154 may be
displayed (e.g., on a display as shown in FIG. 3), and/or audibly
indicated to the user. As another example, any interruption in
communication between the scale 110 and the processor 154 may be
detected and indicated to the user on a display or audibly, etc. as
an alert or warning.
[0075] As shown in FIG. 1, the scale 110 may be equipped with a
receptacle 120 (e.g., bin, bucket, tray) configured to receive the
one or more items to be weighed. The receptacle 120 may include a
raised rim or lip to help contain any fluids that may seep or
escape from the items being weighed.
[0076] Generally, one or more processors 154 may be configured to
execute the instructions that are stored in memory 152 such that,
when it executes the instructions, the processor 152 performs
aspects of the methods described herein. The instructions may be
executed by computer-executable components integrated with the
application, applet, host, server, network, website, communication
service, communication interface, hardware/firmware/software
elements of a user computer or mobile device, wristband,
smartphone, or any combination thereof. The instructions may be
stored on memory or other computer-readable medium such as RAMs,
ROMs, flash memory, EEPROMs, optical devices (e.g., CD or DVD),
hard drives, floppy drives, or any suitable device.
[0077] Generally, in one variation, the processor 154 may be
configured to estimate the first volume of the first fluid in the
weighed item based on a difference between a dry weight of the item
and the wet weight of the item, estimate the second volume of the
first fluid in the container based at least in part on the first
and second user inputs, and estimate a total quantity of the first
fluid based at least in part on the estimated first and second
volumes of the first fluid. The processor 154 may additionally or
alternatively be configured to perform some or all aspects of any
of the variations of the methods described herein. As described
above, the one or more processors 154 may be integrated into a
handheld or mobile device 150. In other variations, the one or more
processors 154 may be incorporated into a computing device or
system, such as a cloud-based computer system, a mainframe computer
system, a grid-computer system, or other suitable computer
system.
[0078] The display 158 may be configured to display one or more of
the estimated volumes of the first fluid and/or estimated total
quantity (or predicted or future trends of loss, etc.) of the first
fluid. The display 158 may be configured to display or otherwise
communicate to a user (e.g., doctor, nurse) other information,
including but not limited to patient information, images of
containers or substrates, etc. The display 158 may include a screen
on a handheld or mobile device, a computer monitor, a television
screen, a projector screen, or other suitable display. In some
variations, the display 158 may be configured to display a user
interface that enables the user to input information (e.g.,
estimated volumes of fluid in one or more containers), select
display options (e.g., font, color, language, etc.) and/or content
(e.g., patient information, fluid-related information, alerts,
etc.). In these variations, the display may be user-interactive and
include a resistive or capacitive touch screen that is responsive
to skin, a stylet, or other user contact. In other variations, the
display 158 may be user-interactive via a cursor controlled by a
mouse, keyboard, or other suitable input device.
[0079] In some variations, the system may additionally or
alternatively include an audio system that communicated information
(e.g., fluid-related information, alerts, etc.) to a user. The
display and/or the audio system may, for example, provide alerts or
alarms upon the estimated quantity of trend of fluid loss meeting a
threshold, which may be useful to prompt certain actions in
response, such as providing a blood transfusion to the patient.
[0080] Furthermore, in some variations, as shown in FIG. 8, a
system 800 for quantifying fluid from a patient may be
substantially similar to the system 100 shown in FIG. 1, except
that the system may additionally or alternatively include a camera
156 or other optical sensor or optical imaging device configured to
generate an image of a container 810 including a third volume of
the fluid of interest. The camera 156 may include at least one
optical image sensor (e.g., CCD, CMOS, etc.) that captures a color
optical digital image with red, green, and blue (RGB) color
components for the pixels, and/or other suitable optical
components. For example, the camera 156 may include a single image
sensor paired with suitable corresponding optics and/or filters
(e.g., color filter arrays such as a Bayer pattern filter). As
another example, the camera 156 may include multiple image sensors
paired with suitable corresponding optics, such as at least one
prism or diffractive surface to divide white light into separate
color channels (e.g., RGB), each of which is detected by a
respective image sensor. However, the camera 156 may include any
suitable image sensor sand other optical components to enable the
camera 156 to generate images.
[0081] The foregoing description, for purposes of explanation, used
specific nomenclature to provide a thorough understanding of the
invention. However, it will be apparent to one skilled in the art
that specific details are not required in order to practice the
invention. Thus, the foregoing descriptions of specific embodiments
of the invention are presented for purposes of illustration and
description. They are not intended to be exhaustive or to limit the
invention to the precise forms disclosed, as many modifications and
variations are possible in view of the above teachings. The
embodiments were chosen and described in order to best explain the
principles of the invention and its practical applications, they
thereby enable others skilled in the art to best utilize the
invention and various embodiments with various modifications as are
suited to the particular use contemplated. It is intended that the
following claims and their equivalents define the scope of the
invention.
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